Sealing arrangement for hinges of track chains

ABSTRACT

Sealing arrangement including an elongated bolt formed with a unilaterally open bore, a bushing coaxial with the bolt and spaced radially outwardly therefrom to form an annular passage between the bolt and bushing, the bushing being integrally provided with opposite support end surfaces, a pair of outer chain link mounted on the bolt and the bushing and forming respective opposite spacers with the respective support surfaces of the bushing, each of the spacers being provided with respective lubricating channels formed in the bushing and communicating with the annular channel for conveying a lubricant from the channel into the spacers and a pair of annular seals each received in the respective spacer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national phase application corresponding toPCT/DE91/00883 filed Nov. 11, 1991 and based in turn, upon a Germanapplication P4039095.0 filed Dec. 7, 1990 under the InternationalConvention.

FIELD OF THE INVENTION

The invention relates to a sealing arrangement for hinges of trackchains wherein the hinge includes of a bolt and a bushing, the outerchain links are secured to the bolt and the inner chain links aresecured to the bushing, whereby the bolt has a reservoir which can befilled with lubricant and is connected particularly via a cross-channelwith the lubrication gap between the bushing and the bolt, the ends ofwhich are sealed off with seals which are sealingly supported on theouter chain links on one side and on the bushing ends on the other side,whereby between each bushing end and each outer chain link adimensionally stable support element is arranged.

BACKGROUND OF THE INVENTION

Such a sealing arrangement is known for instance from DE 31 27 104 C2.In the known sealing arrangement a support ring is arranged on the boltwith play between the bushing ends in a corresponding recess of theouter chain links, the actual elastic seal being supported on theoutside of this ring. The seal rests with its sealing elements or wingson parts of the outer chain links on the one side and on the frontalside of the bushings on the other. In crawlers and the like where thetrack chains are subject to heavy loads it becomes necessary tolubricate the hinges, which, according to the state of the art, is doneby feeding lubricants to a bushing/bolt combination, whereby due to asupport ring--seal connection between the bushing, bolt and chain link alubricant chamber is created in the link area. The drawback of theheretofore known solutions is that the vertical and horizontal forcesgenerated in the hinges between the bushing-support ring-chain link,bushing-support ring-bolt or also between chain link-support ring-boltproduce inner stress, which can have disadvantageous effects on thesealing of the hinge. For instance, it can result in support ringbreakages or in heavy wear of the sealing material.

The above-described sealing arrangement where the lubricants areintroduced as flowable lubricants, as well as sealing arrangements wherethe lubricant reservoir is formed by the chamber wherein the seal isarranged, are known to the state of the art. Thereby grease or similarmaterials with low flowability are used. In this known construction thelubrication gap between the bushing and the bolt is also filled withgrease, as is the chamber containing the seal, namely in the area facingthe lubrication gap. In such constructions the lubricant reservoir inthe bolt proper is eliminated, so that the bolt can be a solid partwithout hollow portions.

OBJECTS OF THE INVENTION

It is the principle object of the invention to provide a sealingarrangement of the generic kind, wherein the action of the forcesgenerated in the hinge is basically limited only to a connection betweenthe bushing and the chain link.

It is a further object of the invention to provide a generic hingehaving components assembled either into a unlubricated, seal-freearrangement or into a lubricated track chain provided with sealingarrangement.

SUMMARY OF THE INVENTION

In order to solve this problem, the invention proposes that the supportelement be formed as an integral part of the bushing ends and thelubricating gap be connected to the receiving space for the seals bylubricating grooves or channels, formed in the frontal surface of theshaped supporting element and/or in the bushing body, and/or lubricationpassages or channels be provided, through which the lubrication gap isconnected with the sealing space.

Due to this construction it is possible to arrange the seal directlybetween the bushing and the outer chain link, without having to providean additional support ring and other comparable elements in the hingespace, which could cause frictional locking. In the actual embodiment ofthe invention the bushing are shaped at their ends, so that when theouter chain links are pressed to bolt size, a frictional connectiondepending on the amount of applied pressure can be achieved between thebushing and the outer chain link and between the outer chain link andthe bushing a sealing space results, which insures the sealing of thehinge in this area due to a correspondingly designed seal. Thesufficient supply of lubricant is achieved alternately or in combinationby providing radial lubrication grooves on the frontal surfaces of thebushing projections or by providing lubrication passages or channelstraversing the bushing body and through which the lubrication gap isconnected with the sealing space.

The design of the seal itself has to be adjusted to the spatialrealities and geometric proportions, whereby the sealing space betweenchain link and bushing has to be optimally used by the seal. Bycorrespondingly adjusting the design of the seal to the labyrinthcontact surface of the chain link, as well as to the correspondingpartial cut of the bushing contact surface a complete and durablesealing can be insured. A round ring of elastic material has to beconsidered as the simplest solution for the seal, whereby other sealshapes and combinations of sealing materials (elastomer materials) arepossible.

Preferably it is also provided that the frontal surface of the shapedsupport element be set at a right angle with respect to the bushingaxis.

Furthermore it is preferred that the surface of the bushing locatedbetween the frontal surface of the shaped support element and thebushing shell be recessed with respect to the frontal surface, wherebythe area of the outer chain link forming the hollow receiving the sealreaches in axial direction over the point where the outer shell of thebushing starts and the bushing is at least slightly overlapped withradial play by the hollow-containing link parts of the outer links.

Finally, it is preferred that the recess between the frontal surface andthe bushing shell be of a stepless design.

Thereby the transition surface between the frontal surface and thebushing shell can be designed as an inclined surface or as a concavelyor convexly curved surface.

A preferred arrangement is the one where the seals are vulcanized to thewalls of the outer chain links or of the bushing forming their receivingspace, whereby the seals are made completely or partially ofvulcanizable material.

Due to this design it is possible to vulcanize the seal to the wallingof the outer chain link or the bushing prior to the assembly of theindividual components, so that a strong fastening is given prior toassembly, and in addition thereto the seal having only a surface actedupon by relative movement, includes the surface which rests against theother respective component. Preferably the arrangement is designed sothat the seal is vulcanized to the walling of the outer chain linksurrounding the receiving space.

A preferred further development consists in that the area of the chainlink forming the hollow in which the seal is received extends in radialdirection only as far as necessary to create a motion clearance (gap)between the cylindric shell area of the bushing overlapped by it and theoverlapping walling area of the chain link.

In the design according to the invention it is possible to introduceidentical components with identical dimensions, independently of thefact whether later a lubricated chain with sealing arrangements or anunlubricated chain without sealing arrangements is supposed to be formedlater out of these components. Basically this arrangement makes alsopossible to use components up to now normally used for unlubricatedchains also for lubricated chains, whereby only corresponding work ofthe bushing part at its frontal surface has to be done, any other workbecoming superfluous.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features, and advantages will become morereadily apparent from the following description, reference being made tothe accompanying drawing in which:

FIG. 1 is a diagrammatic sectional view along the axis of a hinge of atrack chain with sealing arrangement;

FIG. 2 is a partial axial sectional view of one embodiment of thesealing arrangement according to the invention; and

FIG. 3 is partial sectional axial view of another embodiment accordingto the invention;

FIG. 4 is an enlarged sectional view of another embodiment of thesealing arrangement with a convex support surface of the bushingaccording to the invention;

FIG. 5 is still another embodiment of the sealing arrangement includingthe tapered support surface of the bushing and support elements formedon the bushing; and

FIG. 6 is yet further embodiment of the sealing arrangement according tothe invention similar to the one shown in FIG. 5 but having a differentcross-section of the seal.

As seen in FIG. 1 the hinge includes two outer chain links 1, two innerchain links 2, a bolt 3 and a bushing 4. The outer chain links 1 areconnected with bolt 3, for instance, in the manner of a slip-jointconnection, while the inner chain links 2 are connected with the bushing4. The bolt 3 has a bore 5 unilaterally open to the outside, whichserves as a lubricant reservoir. The bore 5 is connected over across-channel 6 with a gap 7 between the bushing 4 and the bolt 3, whichgap is in turn connected with the sealing arrangement 8 arranged in ahollow space of the outer chain links 1. The seals prevent the escape ofthe lubricant towards the outside. Between each end of the bushing 4 andeach outer chain link 1, a dimensionally stable shaped support element20 (FIG. 1) is formed integrally on the bushing ends as seen in FIGS. 1and 2 or mounted on the support surface of the bushing ends as shown inFIGS. 5 and 6, which is shaped in one piece at the bushing end. Therebythe lubrication gap 7 is connected with the space 10 receiving the sealover lubrication grooves 30 (FIG. 7) or lubrication channels 11 shown inFIGS. 1 and 5. The lubrication grooves are arranged optionally radiallyon the frontal surface of the frontal surface of the support element 9,while the lubrication while passages traverse the bushing body and makethe connection between the lubrication gap 7 and the hollow space 10. Inall embodiment examples, the frontal surface of the shaped supportelement 9, 29, 39, 48, 60 and 40 is set at a right angle with respect tothe bushing axis, i.e. parallel to the surface of the hollow space 10 ofthe outer chain link 1 which is oriented at a right angle with respectto the bushing axis. Also in all embodiment examples, the bushingsurface located between the frontal surface of the support element 9(FIG. 1) and the outer shell of the bushing 4 is recessed with respectto the frontal surface of the support element 9, whereby the area of theouter chain links 1 forming the hollow space 10 receiving the sealreaches in axial direction over the starting point of the outer shell ofbushing 4, whereby the bushing is at least slightly overlapped withradial play by the link parts of the outer chain links 1 containing thehollow space 10. In this way no radial access gap to the hollow spaces10 is formed, so that the penetration of dirt or the like in the hollowspace 10 is made more difficult or even prevented to a large extent.

While in the embodiment example according to FIG. 3 the recess betweenthe frontal surface 39 of the support element 9 and the bushing shell ofbushing 4 is designed like a step, in the other embodiment shown in FIG.2 the recess is stepless, namely as shown to the left in FIG. 2 in whichthe support surface is formed as an inclined surface 33. FIGS. 1 and 4show the support surface formed as concave and convex surfacerespectively. FIG. 1 in the lower right side as a convex surface. Theshape of seals 8 can also be selected at will, as well as the option tomake the seals of a homogeneous elastomer material or of a compositeelastomer material. Thus, for example, FIG. 2 illustrates an O-shapedseal 34, while as seen in FIG. 3, the seal 34' has a dome-shaped apartreaching radially outwardly with respect to a bolt axis A.

Preferably the seals are vulcanized to the wallings of the outer chainlink defining the receiving space 10, whereby the seals are madecompletely or at least partially of a vulcanizable material. The sealingarrangement of the invention offers the possibility to use the usualcomponents heretofore used for the production of unlubricated chains. Inthis arrangement the area forming the seal receiving space 10 of theouter chain link 1 extends in radial direction only so much as to allowa motion clearance (gap) between the cylindric outer shell area ofbushing 4 which is overlapped by it and the overlapping walling portionof the chain link 1.

FIG.4 shows an embodiment of the sealing arrangement with the supportsurface 80 which, in this case, is the bushing axial ends curvedradially. The seal 48 has an inner surface 49 formed complementary witha respective support surface and an outer surface 48' and 49'registering respectively with radial and axial walls of the chainlink 1. The support surface, the seal and the walling of the chain linkform the respective space 10 communicating with the annular gap.

I claim:
 1. Track chain hinge assembly comprising:a bolt extending alongan axis; means forming a lubricant reservoir in the bolt; a bushingcoaxial with the bolt and mounted pivotally thereon, the bushing beingformed with opposite ends and with an inner peripheral recess forproviding between the bushing and the bolt an elongated annular gapextending between the ends; flow means for providing a flowcommunication between the reservoir and the gap; a pair of axiallyspaced apart inner chain links mounted on the bushing; a pair of axiallyspaced apart outer chain links mounted on respective ends of the boltand outwardly of said inner chain links and sealing the gap at theopposite ends; means forming a respective recessed portion in each ofthe outer links, each of the ends of the bushing being formed integrallywith a respective support surface received in the respective recessedportion so as to form therewith a respective annular space; seal meansin each annular space for compression in the axial and radial directionswithin each of the recessed portions upon application of thrust forceson the apparatus, the seal means partially filling the annular spaces toform respective annular compartments in each of the recessed portions;and means including a plurality of flow passages traversing the bushingand opening into the respective unfilled compartments for providing aflow communication between said gap and said unfilled compartments. 2.The assembly defined in claim 1 wherein each support surface extends ina plane perpendicular to said axis.
 3. The assembly defined in claim 1wherein each of said support surfaces extending axially inwardly todefine a radial play between the respective outer link and the bushing.4. The assembly defined in claim 1 wherein each of said support surfacesis stepless.
 5. The assembly defined in claim 1 wherein the seal meansis made at least partially of a vulcanizable material vulcanized to thebushing and a wall of said portion.
 6. The assembly defined in claim 1,further comprising an annular support received in the space and incontact with the seal means.